Unable to use concurrent.futures in atexit hook

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-12-15.13:59:10.547>
labels = ['3.9', 'type-crash']
title = 'Unable to use concurrent.futures in atexit hook'
updated_at = <Date 2021-02-01.13:41:43.911>
user = 'https://github.com/jd'

bugs.python.org fields:

activity = <Date 2021-02-01.13:41:43.911>
actor = 'corona10'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = []
creation = <Date 2020-12-15.13:59:10.547>
creator = 'jd'
dependencies = []
files = []
hgrepos = []
issue_num = 42647
keywords = []
message_count = 4.0
messages = ['383058', '385584', '385972', '386067']
nosy_count = 5.0
nosy_names = ['pitrou', 'vstinner', 'jd', 'aeros', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue42647'
versions = ['Python 3.9']